Influence of Space Charge on Dielectric Property and Breakdown Strength of Polypropylene Dielectrics under Strong Electric Field

Xing, Zhaoliang; Gu, Zhenlu; Zhang, Chong; Guo, Shengming; Cui, Huize; Liu, Qingquan; Li, Guochang

doi:10.3390/en15124412

Cited by 9 publications

(4 citation statements)

References 25 publications

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“…The presence of the space charge has a great impact on dielectric breakdown of the material. This phenomenon has been reported by Zhou and Chen [18] and Xing et al [19]. 4.…”

Section: Discussionsupporting

confidence: 72%

Electrical Properties of Polyethylene Terephthalate under Hydrothermal Aging

Ait-Saadi¹,

Nedjar²

2023

MMEP

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During the working of rotating machines, dielectric materials are submitted to the action of humidity. At long term, their properties can degrade and the lifetime of devices will be reduced. This paper deals with the influence of hydrothermal aging on the electrical properties of polyethylene terephthalate. The insulation was aged in water at 80℃ and 100℃. The study shows that dielectric loss factor, permittivity, volume resistivity and dielectric strength were affected by aging. The change is attributed to the fact that the aging reduces molecular bonds causing a decrease in the viscosity. Thereby, the free volume and the mean free path raise. This process leads to the raise in the mobility of charge carriers. The evolution of activation energy versus aging time exhibits minimums and maximums resulting to the plasticization and the crosslinking of the material, respectively. The TGA thermograms indicate a variation of onset temperature with aging time. It was highlighted by TGA that the decomposition occurs following one step. The FTIR analysis points out a change in the intensities of the vibrational spectra after aging. The penetration of water within the dielectric induces differential inflations. The physical chemical analysis shows a modification in the molecular conformation of the polymer. The results are analysed and discussed.

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“…The presence of the space charge has a great impact on dielectric breakdown of the material. This phenomenon has been reported by Zhou and Chen [18] and Xing et al [19]. 4.…”

Section: Discussionsupporting

confidence: 72%

Electrical Properties of Polyethylene Terephthalate under Hydrothermal Aging

Ait-Saadi¹,

Nedjar²

2023

MMEP

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“…DCLCs are subject to a DC field strength of more than 200 V/µm [8]. In engineering technology, dielectric constant, dielectric loss, insulation resistance, and breakdown characteristics are the main insulation performance parameters of dielectrics.…”

Section: Introductionmentioning

confidence: 99%

Effects of Mechanical Stress on the Life and Insulation Performance of DC-Link Capacitors

Sun,

Qiao,

et al. 2024

Energies

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Mechanical stress is a crucial factor affecting the life and insulation performance of DC-link capacitors (DCLCs). However, at present, there is a lack of long-term experimental observations on the effects of mechanical stress on the life and insulation performance of DCLCs. The element-winding process for DCLCs is carried out by winding metalized film on a reel and adjusting the various winding tensions and pressures according to performance requirements, usually with a winding tension coefficient (WTC) of kT = 1.5. The pull pressure of the winding machine on the film produces tension during the elements’ winding process, and the tension in the film grows after the heat-setting process. In this study, by adjusting the four tension coefficients of the elements in the winding process, which were 1.4, 1.5, 1.6, and 1.7, various winding tensions of the DCLC components were changed. Additionally, various heat-setting shrinkage tensions were appropriately generated by setting different heat-setting temperatures (HSTs). Relevant test platforms were established, and a life aging test, insulation resistance measurement, and withstand voltage test were performed on these DCLCs at different tension coefficients and HSTs. The obtained results reveal that the mechanical stress of DCLCs is affected by the parameters of the material itself, including the tension coefficient during the winding process and the HST. The winding tension affects the life of DCLCs, such that those with the highest tension (kT = 1.7) demonstrate the longest life at an HST of 105 °C, whereas samples with the lowest tension (kT = 1.4) exhibit the longest life at an HST of 110 °C. HSTs are capable of improving the lifetime of DCLCs. HSTs are also able to improve the withstand voltage capability of DCLCs, but the tension is not proportional to the withstand voltage capability of DCLCs. This research provides a suitable basis for further explorations of the life and insulation performance of DCLCs.

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“…Smart grid with flexible power technology includes flexible DC transmission project, static synchronous compensator, sub-synchronous resonance device, static reactive power generator, and unified power flow controller. DCLC has been regarded as a core device of converter valves within the smart grid 11,12 . The quantity of DCLC within each flexible DC transmission project of a smart grid can reach tens of thousands in numbers which makes the lifetime of DCLC a critical performance parameter that should be determined by thoroughly evaluating the effect of thermal stress on the capacitor 13 .…”

Section: Introductionmentioning

confidence: 99%

Effect of thermal stress on the life of DC link capacitors for smart grid

Sun,

Qiao,

et al. 2024

Preprint

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Thermal stress is an important factor affecting the life of a DC link capacitor (DCLC). However, relevant studies on thermal stress mechanism directly influencing the lifetime of the capacitor are rarely reported. In this paper, the thermal polymerization of DCLC has been analyzed, and the relevant experimental platforms have been developed to evaluate the breakdown strength of DCLC at two thermal polymerization temperatures (TPTs). Simultaneously, the aging analysis of DCLC at different TPTs and the accelerated lifetime measurements at various temperatures were also executed to attain insights into the influence of thermal stress on the lifetime of DCLC. The results showed that the stress caused by thermal polymerization and working temperature influenced the breakdown voltage capability and the lifetime of DCLC. With an increase in TPT by 5 °C, a step-increase in the withstand voltage capability of DCLC from 7,000 V to 7,200 V was observed that demonstrated an enhancement of 2.86%in the breakdown strength performance. Correspondingly, the lifetime of DCLC with a capacitance change rate of -3% enhanced from 1,500 hours to 1,700 hours. However, severe deterioration in the life span of DCLC from 4,200 hours to 500 hours was observed with an increasing operating temperature from 55 °C to 85 °C, respectively. The lifetime could be enhanced by increasing the thermal polymerization temperature as well as reducing the working temperature. The presented results could be termed a harbinger for industrial production of high-performance DCLC with enhanced lifetime that augers well for high-power applications.

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Influence of Space Charge on Dielectric Property and Breakdown Strength of Polypropylene Dielectrics under Strong Electric Field

Cited by 9 publications

References 25 publications

Electrical Properties of Polyethylene Terephthalate under Hydrothermal Aging

Electrical Properties of Polyethylene Terephthalate under Hydrothermal Aging

Effects of Mechanical Stress on the Life and Insulation Performance of DC-Link Capacitors

Effect of thermal stress on the life of DC link capacitors for smart grid

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